An average of 13 per cent of ocean-going ships calling at Hong Kong each day have registered with the government's low-sulphur fuel incentive scheme, which aims to cut pollution from vessels, a South China Morning Post investigation found.

The percentage is higher for massive container ships using Kwai Chung container port. The survey showed almost one in four container ships using Kwai Chung registered with the Environmental Protection Department (EPD) programme, launched at the end of October.

Former Marine Department director Roger Tupper was surprised the figures were so high.

The Post investigation, which tracked vessel arrivals and departures over a week, found around 70 large container ships, tankers, general cargo vessels and cruise liners visited Hong Kong each day. Of these about eight or nine are signed up to the scheme, which will cost the government HK$260 million over three years.

Around 550 ships were registered with the EPD scheme up to mid-December, of which 192 had made a total of 460 calls at Hong Kong by the end of November. Some HK$2.45 million in port dues had been waived, according to a department spokeswoman.

Operators of ships registered under the scheme receive a 50 per cent cut in port-related fees if the vessels burn low-sulphur fuel while berthed in Hong Kong.

But the scheme has been criticised, as the rebate only offsets between 30 and 45 per cent of the increased cost of using the more expensive low-sulphur diesel.

The scheme also sidesteps a key demand from environmentally aware shipping lines for government regulations mandating the use of low-sulphur diesel.

Civic Exchange, the public policy think tank, said marine sources of sulphur dioxide emissions accounted for 519 premature deaths a year in the Pearl River Delta, including 385 in Hong Kong. Some 75 to 80 per cent of all emissions come from container vessels, it said.

The Post found that some shipping lines are enthusiastic supporters of the EPD scheme, registering massive fleets even though they face higher costs. These include Orient Overseas Container Line, Maersk Line, CMA CGM and Hapag-Lloyd.

But other container lines, like Singapore's APL, have either yet to register any ships or have registered just a handful, even though they were signatories to the Fair Winds Charter, a voluntary industry initiative to use low-sulphur fuel in Hong Kong.

While the EPD has introduced its incentive scheme, regulations have yet to materialise.